This invention relates to the production and use of antioxidant compositions, including what are believed to be new products having unusual advantages in preventing or inhibiting the deterioration of fats and oils, particularly in food materials, that is caused by oxidation. As is well known, fats and oils become rancid or otherwise unpleasant as to flavor or odor by reason of oxidation effects. A number of chemical compounds have been employed for avoiding or reducing these effects, i.e. so that the fats and oils, or foods containing them, may be kept for longer periods of time, but such agents have not been entirely satisfactory or effective in many cases. Furthermore, they are chemical products not derived from or identical with material of natural food classifications, and there has been some question about the advisability of using them.
Principal antioxidants of the above kinds heretofore employed have included so-called BHA (butylated hydroxyanisole) and so-called BHT (butylated hydroxytoluene), and so-called TBHQ (tertiary butylhydroquinone), as well as some other chemicals of which one example is propyl gallate (PG). While these materials have been quite effective in animal fats, such as lard, they are much less useful in some other applications. Their volatility and tendency to decompose at high temperatures make them not entirely suitable for deep fat fried foods. Indeed their usefulness for the stability of vegetable oils is less than satisfactory. For example, they are not entirely effective in protecting certain off-flavor development such as the so-called reversion flavor that occurs, with passage of time, in soybean oil. For these and other reasons there has been a need for improvement in the field of antioxidants, especially those to be used with food materials that comprise or consist of fats or oils.
It has heretofore been found that antioxidant properties are possessed by certain natural vegetable materials in the class sometimes identified as herbs, and particularly in the specific plants rosemary and sage, which are commonly used as spices. Indeed it has been found that by extracting the fresh or dried leaves or like parts of these plants, such as rosemary, by the use of alcohol or similar readily volatile solvent a somewhat concentrated but crude preparation may be obtained which has considerable antioxidant effect. Procedures have been proposed for making such crude extract, in most instances directly from the leaves, stems or the like of the natural spice, or in some cases by alcohol treatment of the plant material after the oil of the spice (present in very minor proportion) has been substantially removed by steam distillation. The resulting crude extract in alcohol or like liquid has been evaporated (sometimes after some bleaching with active carbon) to yield a solid product. While such product can be considered as in some respect refined in contrast with the original leaves and stems of the spice plant, and indeed although such products have been described as purified and of substantially less taste or odor than the natural spice, these materials have not by any means been fully freed of the characteristically pungent, natural aroma and flavor, with some bitterness, of the basic spice material. Accordingly, although such preparations have been found to provide antioxidant properties, and one such product is currently available on the market, the use of these materials is limited to situations where the basic flavor of the spice is wanted or at least tolerated.
So far as can be ascertained, essentially tasteless and odorless antioxidant materials are limited to substances such as those of the manufactured chemical character mentioned above, and indeed it can be said that there is a real need in the food industry for an antioxidant extracted from natural food stuffs, that has superior properties and can serve a wide range of uses.